恒星、黑洞与星系的类型
这里几乎所有天体都是同一个问题的答案：恒星诞生时有多重？质量决定它燃烧得多热、活多久，以及留下什么——缓慢冷却的余烬、城市大小的中子球，或时空中的一个洞。三十四个天体，从恒星凝结而出的冷云到宇宙中最大的结构，全部以真实交互式 3D 呈现。
这里的黑洞不是示意图。光线在弯曲时空中被逐步积分，因此阴影、光子环、翻折到上方的吸积盘以及背景星场中的爱因斯坦环，都来自物理本身而非贴图。同一个积分器只需替换度规或视界，就能画出自转黑洞、并合双黑洞和虫洞。
冷气体、暗云，以及新生恒星周围形成的盘。本页后面的一切都从这里开始，包括构成你的原子。
Molecular Cloud
The coldest, darkest thing in the galaxy — and where every star comes from.
Emission Nebula
A molecular cloud with the lights switched on, being destroyed by its own children.
Protoplanetary Disk
A solar system caught in the act of assembling itself.
被引力束缚、由核聚变支撑的等离子体球。它们的一生由诞生时的一个数字决定：质量。
Main-Sequence Star
A star in the long, stable middle of its life. The Sun is one.
Red Dwarf
The most common star in the galaxy, and the last one still burning.
Red Giant
A dying star, swollen to hundreds of times its old size.
Blue Supergiant
Burns a million times brighter than the Sun, and dies in a few million years.
Wolf-Rayet Star
A star so hot it is blowing its own atmosphere into space.
Brown Dwarf
Too heavy to be a planet, too light to ever be a star.
燃料耗尽后剩下的东西——物质被压缩到只剩量子力学在支撑它。
Planetary Nebula
A dying star's outer layers, lit from inside by the core it left behind.
White Dwarf
The Sun compressed to the size of Earth, cooling for eternity.
Black Dwarf
The end of a white dwarf. The universe is far too young for one to exist.
Neutron Star
A city-sized object with more mass than the Sun.
Pulsar
A lighthouse spinning up to 700 times a second.
Magnetar
The strongest magnets in the universe, by a factor of a trillion.
Quark Star
A star where even neutrons have been crushed into their parts.
Supernova Remnant
The wreckage of a dead star, still expanding at thousands of km/s.
超过某个质量后，已知的力都无法阻止坍缩。剩下的只有纯粹的几何：时空中的单向面。
Stellar-Mass Black Hole
A star heavy enough that nothing could stop the fall.
Intermediate-Mass Black Hole
The class that was missing from the census for fifty years.
Supermassive Black Hole
One sits at the heart of nearly every galaxy, including ours.
Spinning Black Hole
Every real black hole is this one. Spin drags spacetime around with it.
Binary Black Hole
Two shadows, each lensing the other, spiralling toward a merger.
Quasar
A feeding black hole outshining every star in its galaxy combined.
Blazar
A quasar that happens to be pointing its jet straight at us.
Primordial Black Hole
Born in the first second of the universe, and possibly still here.
广义相对论的解，不需要任何恒星死亡就能产生。其中两种从未被观测到，一种很可能根本无法存在——这正是值得看一眼的理由。
Wormhole
Not a hole. A window — with a different universe on the other side.
White Hole
The same equations run backwards: nothing can get in, and it never stops pouring out.
Boson Star
Mass without matter, gravity without a surface, and no shadow at all.
拉远到足够尺度，单颗恒星就不再重要，剩下的只是它们的排列方式——盘、球、星团，最终汇成宇宙中最大的图案。
Spiral Galaxy
Arms that survive because they are a traffic jam, not a structure.
Barred Spiral Galaxy
The Milky Way. A straight bar of stars feeding the centre.
Elliptical Galaxy
The largest galaxies there are, and nothing has been born in them for billions of years.
Irregular Galaxy
No disc, no bulge, no plan — and making stars faster than anything its size.
Globular Cluster
A million stars in a sphere, and older than the galaxy they orbit.
Cosmic Web
Every galaxy in the universe strung along filaments around enormous empty voids.
一个数字决定一切
恒星的一生恒星无法选择自己的结局。它从气体云中坍缩成形时所拥有的质量，决定了它燃烧得多热、存在多久，以及将走上以下五条路径中的哪一条。其余的一切——颜色、大小、光度、最终留下什么——都由这一个数字推导而来。
| 天体 | 质量 | 半径 | 温度 | 寿命 |
|---|---|---|---|---|
| Molecular Cloud | 10^3 - 10^7 M(sun) | 15 - 600 light years | 10 - 20 K | ~10 - 30 Myr |
| Emission Nebula | 10^2 - 10^5 M(sun) | 1 - 100 light years | ~10,000 K | ~1 - 5 Myr |
| Protoplanetary Disk | 0.001 - 0.1 M(sun) | 10 - 1,000 AU | 20 - 1,500 K | ~1 - 10 Myr |
| Main-Sequence Star | 0.08 - 150 M(sun) | 0.1 - 15 R(sun) | 2,400 - 50,000 K | 10 Myr - 10 Tyr |
| Red Dwarf | 0.08 - 0.45 M(sun) | 0.1 - 0.6 R(sun) | 2,300 - 3,900 K | up to 10 trillion yr |
| Red Giant | 0.3 - 8 M(sun) | 10 - 1,000 R(sun) | 3,000 - 5,000 K | ~1 billion yr in phase |
| Blue Supergiant | 10 - 100 M(sun) | 20 - 200 R(sun) | 10,000 - 50,000 K | 3 - 30 million yr |
| Wolf-Rayet Star | 10 - 25 M(sun) now | 1 - 25 R(sun) | 30,000 - 210,000 K | a few 100,000 yr |
| Brown Dwarf | 13 - 80 M(Jupiter) | ~1 R(Jupiter) | 250 - 2,500 K | cools forever |
| Planetary Nebula | 0.1 - 1 M(sun) shell | 0.1 - 3 light-years | Core 30,000 - 200,000 K | ~20,000 yr |
| White Dwarf | 0.17 - 1.4 M(sun) | ~1 R(Earth) | 4,000 - 150,000 K | cools for 10^15 yr |
| Black Dwarf | 0.17 - 1.4 M(sun) | ~1 R(Earth) | Background cold | Effectively forever |
| Neutron Star | 1.1 - 2.3 M(sun) | ~11 km | ~600,000 K surface | cools for billions of yr |
| Pulsar | ~1.4 M(sun) | ~11 km | Beamed radio to gamma | spins down over Myr |
| Magnetar | ~1.4 M(sun) | ~11 km | Field 10^14 - 10^15 gauss | active ~10,000 yr |
| Quark Star | 1.5 - 2.5 M(sun) | ~8 - 11 km | 10^6 - 10^11 K | Indefinite |
| Supernova Remnant | 1 - 20 M(sun) ejected | grows to 100+ ly | 10^6 - 10^7 K shock | ~100,000 yr |
| Stellar-Mass Black Hole | 3 - 150 M(sun) | 9 - 450 km horizon | Disk 10^7 K | 10^67 yr to evaporate |
| Spinning Black Hole | Any | Horizon shrinks with spin | Disc to 10^7 K | Spin decays over Gyr |
| Binary Black Hole | 2 x (5 - 100) M(sun) | Separation shrinks to zero | Disc to 10^6 K | Myr to Gyr, then seconds |
| Intermediate-Mass Black Hole | 100 - 100,000 M(sun) | 300 km - 300,000 km | Disk 10^6 K | gigayears |
| Supermassive Black Hole | 10^5 - 10^10 M(sun) | up to 1,300 AU horizon | Disk 10^5 - 10^6 K | 10^100 yr to evaporate |
| Quasar | 10^8 - 10^10 M(sun) | disk ~ light-days | Disk up to 10^5 K | ~10 - 100 Myr active |
| Blazar | 10^8 - 10^10 M(sun) | Jet up to Mpc | Gamma-ray dominated | Flares in hours |
| Primordial Black Hole | 10^-8 - 10^5 M(sun) | atom to kilometres | Hawking glow | set by mass |
| Wormhole | Negative (exotic) | Throat radius, free parameter | None | Unstable without exotic matter |
| White Hole | Any | Same as a black hole | Surface emission, unbounded | Violently unstable |
| Boson Star | Set by particle mass | Compact, no surface | None | Stable if below critical mass |
| Globular Cluster | 10^4 - 10^6 M(sun) | 30 - 300 light years | Stars 3,000 - 8,000 K | > 12 Gyr |
| Irregular Galaxy | 10^8 - 10^10 M(sun) | 3,000 - 30,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Spiral Galaxy | 10^10 - 10^12 M(sun) | 15,000 - 150,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Barred Spiral Galaxy | 10^10 - 10^12 M(sun) | 15,000 - 150,000 ly | Stars 3,000 - 40,000 K | > 10 Gyr |
| Elliptical Galaxy | 10^8 - 10^13 M(sun) | 3,000 - 700,000 ly | Stars 3,000 - 6,000 K | > 10 Gyr |
| Cosmic Web | ~10^53 kg observable | Filaments 10^8 ly | Voids near 0 K | Age of the universe |
恒星有哪些类型？
恒星按温度分为 O、B、A、F、G、K、M 光谱序列，按体积分为矮星、巨星和超巨星。实际常用的分类是红矮星、类太阳主序星、红巨星、蓝超巨星，以及始终未能点燃氢聚变的次恒星级褐矮星。
黑洞有哪些类型？
按质量可分为四类：由恒星坍缩形成的恒星级黑洞（3 至 150 倍太阳质量）；中等质量黑洞（100 至 10 万倍太阳质量）；位于星系中心的超大质量黑洞；以及假说中在宇宙大爆炸后第一秒内形成的原初黑洞。
中子星和黑洞有什么区别？
两者都是坍缩的恒星核心，但中子星仍有表面：中子简并压和强相互作用将其支撑在约 22 公里的直径上。一旦超过约 2.3 倍太阳质量，就没有任何力量能抵抗引力，坍缩越过事件视界，形成黑洞。
恒星死亡时会发生什么？
取决于质量。约 8 倍太阳质量以下的恒星会膨胀成红巨星，抛掉外层，留下一颗白矮星。更重的恒星会以超新星形式爆发，留下中子星；若坍缩核心超过约 2.3 倍太阳质量，则留下黑洞。
这些 3D 模型在物理上准确吗？
它们由物理计算生成，而非美术绘制。黑洞场景在史瓦西时空中对光线路径进行积分，因此阴影、光子环、被引力透镜扭曲的吸积盘、相对论性多普勒增亮和爱因斯坦环都是算出来的。恒星使用与温度对应的颜色、临边昏暗和对流米粒组织。尺寸为便于观看而取景，并非等比例。